1. Field of the Invention
The present invention relates to compression-ignition engines with electronic control modules programmable for controlling engine temperature by derating torque output of the engine.
2. Background Art
A vehicle engine can be damaged if overdriven at high engine temperatures. The temperatures at which the damage can occur vary depending on the engine. The upper limit temperature for safe engine operation often depends on the number of cylinders, and other structural parameters of the vehicle engine.
One means to prevent the engine from reaching relatively high temperatures relates to controllably reducing the engine temperature by torque derating. Torque derating generally relates to derating, i.e. controllably limiting, torque output of the engine relative to its normal torque output for the current engine operating conditions.
The derating prevents the engine from producing higher levels of torque, which consequently prevents the engine from operating at the elevated temperatures associated with the higher levels of torque. Because the torque levels producing the damaging temperatures are no longer reachable, the engine begins to cool. In this manner, the torque derating can be used to limit the engine from overheating or reaching other temperature levels which may cause damage, unnecessary wear, or produce other debilitating effects.
Past derating techniques were limited in that the derating was controlled relative to predefined temperature thresholds, typically an engine temperature representation based on a measured coolant temperature, oil temperature, or intake/exhaust air temperature.
These existing techniques are simplistic in that only a temperature measurement and a threshold are taken into consideration. There is a need for an enhanced technique that recognizes and overcomes shortcomings of these existing techniques.